| Bristol Diamonds | |
|---|---|
 An example of Bristol Diamonds | |
| General | |
| Category | mineral |
| Formula (repeating unit) | Silica (silicon dioxide, SiO2) |
| Crystal system | hexagonal |
| Identification | |
| Color | Colorless, white, purple, yellow, pink |
| Crystal habit | 6-sided prism ending in 6-sided pyramid (typical), drusy, fine-grained to microcrystalline |
| Mohs scale hardness | 7 |
| Luster | Vitreous |
| Diaphaneity | Transparent to nearly opaque |
| Specific gravity | 2.65 |
| Solubility | Insoluble at STP; 1 ppmmass at 400 °C and 500 lb/in2 to 2600 ppmmass at 500 °C and 1500 lb/in2 |
| References | [1][2][3][4] |
Bristol Diamonds are quartz crystals found in geodes and geological rock formations which occur in dolomitic conglomerate in the Avon Gorge in Bristol, England. Their origin lies in geological processes of the Triassic period, about 250 to 200 million years ago.
The Bristol Diamonds became popular novelties for visitors to the spa at Hotwells, Bristol, during the eighteenth and nineteenth centuries. Diarist John Evelyn and travel writer Celia Fiennes were amongst those who described them. In popular culture they became a synonym for something bright but worthless.
- ^ "Quartz" (PDF). RRUFF Project database. Mineral Data Publishing. 2001. Retrieved 16 March 2010.
- ^ Ralph, Jolyon; Chau, Ida (2010). "Quartz". The Mineral and Locality Database. mindat.org. Retrieved 16 March 2010.
- ^ Barthelmy, David (2009). "Quartz Mineral Data". Mineralogy Database. David Barthelmy. Retrieved 16 March 2010.
- ^ Hurlbut, Cornelius S.; Klein, Cornelis (1985). Manual of Mineralogy (20 ed.). ISBN 0-471-80580-7.